It is desirable to pick up only desired sound (user's voice) during a telephone call, voice recognition, voice recording, or the like. However, sound (e.g., background noise) other than the desired sound may also be present in a usage environment of a voice input device. Therefore, a voice input device having a noise removal function has been developed.
As technology that removes noise in a usage environment in which noise is present, a method that provides a microphone with sharp directivity, and a method that detects the travel direction of sound waves utilizing the difference in sound wave arrival time and removes noise by signal processing have been known.
In recent years, since electronic instruments have been increasingly scaled down, technology that reduces the size of a voice input device has become important. JP-A-7-312638, JP-A-9-331377, and JP-A-2001-186241 disclose related-art technologies.